Background: Cerebral blood vessels are mainly supplied by sympathetic nerves arising from the superior cervical ganglia and cerebral blood volume may be influenced by bilateral superior cervical ganglionectomy (SCG). ...Background: Cerebral blood vessels are mainly supplied by sympathetic nerves arising from the superior cervical ganglia and cerebral blood volume may be influenced by bilateral superior cervical ganglionectomy (SCG). Various stages of cerebral blood volume changes depended on the time following bilateral excision of SCG. In this study, we emphasize the subacute effect (two weeks) on the local cerebral blood flow (LCBF). Material and Methods: Sprague-Dawley rats weighing 250 ~ 400 gm (n = 20) were selected into two groups. Under the ambient temperature 20oC, the first group animals (n = 10) received sham operation and the other group animals (n = 10) underwent bilateral SCG. The LCBF and O2 delivery of 14 brain struc-tures were measured for each animal by the use of 14C-iodoantipyrine technique two weeks after the opera-tion. Results: The average of LCBF was decreased from 150 ml/100 gm/min to 129 ml/100 gm/min after bi-lateral SCG. Only the LCBF at basal ganglia was increased from 108 ml/min/100 g in the sham-operated group to 118 ml/min/100g in the SCG group. A mean of 14% reduction of LCBF was estimated. In 14 brain structures, the delivery amount of O2 was all decreased, except in basal ganglia. However, these changes of LCBF and the delivery amount of O2 at these 14 brain structures did not reach the significant differences. Conclusions: The present results show that chronic effect (two weeks) of bilateral SCG on LCBF was not only in a decrease of the LCBF, but also a decrease of local cerebral O2 delivery. However, the changes didn’t show the significant differences.展开更多
The benefits or detriments of caffeine on the human cardiovascular system have not been thoroughly studied and are still poorly understood. In a world where caffeinated beverages are evidently the adult drug of choice...The benefits or detriments of caffeine on the human cardiovascular system have not been thoroughly studied and are still poorly understood. In a world where caffeinated beverages are evidently the adult drug of choice (e.g. coffee, energy drinks, soda, tea),?investigating its effects on our bodies is of great importance. In this study,?we examined the effects of caffeine, taken as a tablet, on pressure-flow autoregulation. Young adults between 18 and 21 years of age were the experimental subjects. They were instrumented to monitor systemic arterial blood pressure, peripheral blood flow, calculated peripheral vascular resistance, and the electrocardiogram during an autoregulatory maneuver in the absence and presence of caffeine. Caffeine-mediated vasoconstriction was observed as early as 15 minutes after its consumption. Sixty minutes post-caffeine, vasoconstriction was so prominent that autoregulation was abolished. This was reflected, in part, as a significant reduction in blood flow that accompanied a 3-fold increase in calculated peripheral resistance and a significant increase in systemic arterial pressure. Heart rate was unaffected by caffeine under our experimental conditions. We conclude that caffeine has the ability to inhibit significant cardiovascular properties including pressure-flow autoregulation. Even though more work is needed, the significant caffeine-mediated changes in flow, pressure and resistance during autoregulation could have serious consequences for the cardiovascular system specifically, and for one’s overall health in general.展开更多
文摘Background: Cerebral blood vessels are mainly supplied by sympathetic nerves arising from the superior cervical ganglia and cerebral blood volume may be influenced by bilateral superior cervical ganglionectomy (SCG). Various stages of cerebral blood volume changes depended on the time following bilateral excision of SCG. In this study, we emphasize the subacute effect (two weeks) on the local cerebral blood flow (LCBF). Material and Methods: Sprague-Dawley rats weighing 250 ~ 400 gm (n = 20) were selected into two groups. Under the ambient temperature 20oC, the first group animals (n = 10) received sham operation and the other group animals (n = 10) underwent bilateral SCG. The LCBF and O2 delivery of 14 brain struc-tures were measured for each animal by the use of 14C-iodoantipyrine technique two weeks after the opera-tion. Results: The average of LCBF was decreased from 150 ml/100 gm/min to 129 ml/100 gm/min after bi-lateral SCG. Only the LCBF at basal ganglia was increased from 108 ml/min/100 g in the sham-operated group to 118 ml/min/100g in the SCG group. A mean of 14% reduction of LCBF was estimated. In 14 brain structures, the delivery amount of O2 was all decreased, except in basal ganglia. However, these changes of LCBF and the delivery amount of O2 at these 14 brain structures did not reach the significant differences. Conclusions: The present results show that chronic effect (two weeks) of bilateral SCG on LCBF was not only in a decrease of the LCBF, but also a decrease of local cerebral O2 delivery. However, the changes didn’t show the significant differences.
文摘The benefits or detriments of caffeine on the human cardiovascular system have not been thoroughly studied and are still poorly understood. In a world where caffeinated beverages are evidently the adult drug of choice (e.g. coffee, energy drinks, soda, tea),?investigating its effects on our bodies is of great importance. In this study,?we examined the effects of caffeine, taken as a tablet, on pressure-flow autoregulation. Young adults between 18 and 21 years of age were the experimental subjects. They were instrumented to monitor systemic arterial blood pressure, peripheral blood flow, calculated peripheral vascular resistance, and the electrocardiogram during an autoregulatory maneuver in the absence and presence of caffeine. Caffeine-mediated vasoconstriction was observed as early as 15 minutes after its consumption. Sixty minutes post-caffeine, vasoconstriction was so prominent that autoregulation was abolished. This was reflected, in part, as a significant reduction in blood flow that accompanied a 3-fold increase in calculated peripheral resistance and a significant increase in systemic arterial pressure. Heart rate was unaffected by caffeine under our experimental conditions. We conclude that caffeine has the ability to inhibit significant cardiovascular properties including pressure-flow autoregulation. Even though more work is needed, the significant caffeine-mediated changes in flow, pressure and resistance during autoregulation could have serious consequences for the cardiovascular system specifically, and for one’s overall health in general.
